Speaker
Description
Generalized Parton Distributions (GPDs) provide the opportunity to obtain a 3-dimensional description of a nucleon in terms of its constituent partons. Moreover, GPDs are related, via QCD-based sum rules, to total angular momentum, mass and pressure distributions inside the nucleon. GPDs are experimentally accessible via the deeply virtual Compton scattering (DVCS), i.e. the absorption of a highly virtual photon by the proton and the subsequent emission of a high-energy photon.
At Jefferson Lab, the brand new CLAS12 spectrometer has been commissioned and has collected its first DVCS data with a 10.6 GeV continuous electron beam in winter 2017 - spring 2018. Its central part, containing the cylindrical silicon and micromegas trackers within a 5T-solenoidal field surrounding the liquid hydrogen target, is ideal to detect the recoil proton of a DVCS event. The forward detectors, placed in a toroidal magnetic field, detect the associated scattered electron and high energy photon. A first look at the data collected so far with CLAS12 for DVCS studies on unpolarized proton target will be presented together with projections for the full run.
